The United Nations says convoys carrying "life-saving aid" have reached five besieged areas of Syria.

UN officials said trucks carrying food, medical equipment, and medicine for almost 100,000 people had reached rebel-held Madaya, Muadhamiya, and Zabadani near Damascus, and pro-government northern villages of Foah and Kefraya on February 17.

Humanitarian supplies reached some of the areas last month amid reports of people starving.

According to the UN, nearly half a million people live in besieged areas in Syria.

The deliveries are part of an agreement, approved by the International Syria Support Group, that envisages a "cessation of hostilities" by February 19.

But offensives by Syrian government forces and Kurdish militia fighters on rebel-held areas in the country's north have dimmed hopes of a truce.